我有一个包含股票交易的表格:
+------+----------------------+------------------+
| Item | Running Stock Total | Transaction Time |
+------+----------------------+------------------+
| foo | 4 | 2012-05-12 11:07 |
| bar | 3 | 2012-05-12 10:42 |
| bar | 3 | 2012-05-12 9:42 |
| bar | 2 | 2012-05-11 15:42 |
| foo | 3 | 2012-05-11 10:02 |
| bar | 3 | 2012-05-10 13:44 |
...etc...
+------+----------------------+------------------+
即任何时候库存发生变化,都会在此表中创建一行 - 这可能意味着库存水平上升(订购新库存)、下降(库存已售出)或保持不变(库存已搬迁)。
我需要创建一个 sql 查询,它只返回特定零件的库存水平实际发生变化的行,并且它需要在“库存增加”和“库存减少”列中显示变化。
即1 Item='bar'
+------+-----------+------------+----------------------+------------------+
| Item | Stock Up | Stock Down | Running Stock Total | Transaction Time |
+------+-----------+------------+----------------------+------------------+
| bar | 1 | 0 | 3 | 2012-05-12 9:42 |
| bar | 0 | 1 | 2 | 2012-05-11 15:42 |
| bar | 1 | 0 | 3 | 2012-05-10 13:44 |
+------+-----------+------------+----------------------+------------------+
例如 2 Item='foo'
+------+-----------+------------+----------------------+------------------+
| Item | Stock Up | Stock Down | Running Stock Total | Transaction Time |
+------+-----------+------------+----------------------+------------------+
| foo | 1 | 0 | 4 | 2012-05-12 11:07 |
| foo | 2 | 0 | 3 | 2012-05-11 10:02 |
+------+-----------+------------+----------------------+------------------+
所以像...
SELECT
Item, {xyz} as 'Stock Up', {abc} as 'Stock Down', `Running Stock Total`, `Transaction Time`
FROM
`StockTransactions`
WHERE
`Item`='foo'
HAVING
('Stock Up'>0 or 'Stock Down'>0)
这可以做到吗?
最佳答案
SELECT `Item`,
`Stock Up`,
`Stock Down`,
`Running Stock Total`,
`Transaction Time`
FROM (
SELECT `Item`,
GREATEST(`Running Stock Total` - @`last_total`, 0) AS `Stock Up`,
GREATEST(@`last_total` - `Running Stock Total`, 0) AS `Stock Down`,
`Running Stock Total`,
`Transaction Time`,
@`last_total` := `Running Stock Total`
FROM `StockTransactions` JOIN (SELECT @`last_total` := 0) AS lt
WHERE `Item` = 'bar'
ORDER BY `Transaction Time` ASC
) AS t
ORDER BY `Transaction Time` DESC
查看 sqlfiddle .如果您希望结果按事务时间的升序排列并带有额外的 last_total
列,则显然可以省略外部查询。
关于mysql - SQL 查询以显示对 "total"列的更改,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10683748/